package Mojo::IOLoop;
use Mojo::Base -base;

use Carp 'croak';
use Mojo::IOLoop::Client;
use Mojo::IOLoop::Delay;
use Mojo::IOLoop::Server;
use Mojo::IOLoop::Stream;
use Mojo::IOWatcher;
use Mojo::Util 'md5_sum';
use Scalar::Util qw/blessed weaken/;
use Time::HiRes 'time';

use constant DEBUG => $ENV{MOJO_IOLOOP_DEBUG} || 0;

has client_class => 'Mojo::IOLoop::Client';
has iowatcher    => sub {
  my $class = Mojo::IOWatcher->detect;
  warn "MAINLOOP ($class)\n" if DEBUG;
  my $watcher = $class->new;
  $watcher->on(error => sub { warn pop });
  return $watcher;
};
has cleanup_interval => '0.025';
has [qw/lock unlock/];
has max_accepts     => 0;
has max_connections => 1000;
has server_class    => 'Mojo::IOLoop::Server';
has stream_class    => 'Mojo::IOLoop::Stream';

# Ignore PIPE signal
$SIG{PIPE} = 'IGNORE';

sub client {
  my $self = shift;
  $self = $self->singleton unless ref $self;
  my $cb = pop;
  my $args = ref $_[0] ? $_[0] : {@_};

  # New client
  my $client = $self->client_class->new;
  my $id     = $args->{id} || $self->_id;
  my $c      = $self->{connections}->{$id} ||= {};
  $c->{client} = $client;
  $client->iowatcher($self->iowatcher);
  weaken $client->{iowatcher};

  # Events
  weaken $self;
  $client->on(
    connect => sub {
      my $handle = pop;

      # New stream
      my $c = $self->{connections}->{$id};
      delete $c->{client};
      my $stream = $c->{stream} = $self->stream_class->new($handle);
      $self->stream($stream => $id);

      # Connected
      $self->$cb($stream);
    }
  );
  $client->on(
    error => sub {
      my $c = delete $self->{connections}->{$id};
      $self->$cb(undef, pop);
    }
  );

  # DEPRECATED in Leaf Fluttering In Wind!
  $args->{timeout} ||= $self->{connect_timeout};

  # Connect
  $client->connect($args);

  return $id;
}

# DEPRECATED in Leaf Fluttering In Wind!
sub connect {
  my $self = shift;
  $self = $self->singleton unless ref $self;
  my $args = ref $_[0] ? $_[0] : {@_};
  warn
    "Mojo::IOLoop->connect is DEPRECATED in favor of Mojo::IOLoop->client!\n";

  my $id;
  $id = $self->client(
    $args => sub {
      my ($self, $stream, $error) = @_;

      my $c = $self->{connections}->{$id};
      $c->{$_} = delete($args->{"on_$_"}) || $c->{$_}
        for qw/close connect error read/;
      if ($error) {
        $c->{error}->($self, $id, $error) if $c->{error};
        return;
      }

      $stream->on(
        close => sub {
          my $c = $self->{connections}->{$id};
          $c->{close}->($self, $id) if $c->{close};
        }
      );
      $stream->on(
        error => sub {
          my $c = $self->{connections}->{$id};
          $c->{error}->($self, $id, pop) if $c->{error};
        }
      );
      $stream->on(
        read => sub {
          my $c = $self->{connections}->{$id};
          $c->{read}->($self, $id, pop) if $c->{read};
        }
      );
      $c->{connect}->($self, $id) if $c->{connect};
    }
  );

  return $id;
}

# DEPRECATED in Leaf Fluttering In Wind!
sub connect_timeout {
  my ($self, $timeout) = @_;
  warn <<EOF;
Mojo::IOLoop->connect_timeout is DEPRECATED in favor of the timeout argument!
EOF
  if ($timeout) {
    $self->{connect_timeout} = $timeout;
    return $self;
  }
  return $self->{connect_timeout};
}

# DEPRECATED in Leaf Fluttering In Wind!
sub connection_timeout {
  warn <<EOF;
Mojo::IOLoop->connection_timeout is DEPRECATED in favor of
Mojo::IOLoop->timeout!
EOF
  shift->timeout(@_);
}

sub defer { shift->timer(0 => @_) }

sub delay {
  my ($self, $cb) = @_;
  $self = $self->singleton unless ref $self;

  my $delay = Mojo::IOLoop::Delay->new;
  $delay->ioloop($self);
  weaken $delay->{ioloop};
  $delay->once(finish => $cb) if $cb;

  return $delay;
}

sub drop {
  my ($self, $id) = @_;
  $self = $self->singleton unless ref $self;
  if (my $c = $self->{connections}->{$id}) { return $c->{finish} = 1 }
  $self->_drop($id);
}

sub generate_port { Mojo::IOLoop::Server->generate_port }

sub is_running {
  my $self = shift;
  $self = $self->singleton unless ref $self;
  return $self->{running};
}

# DEPRECATED in Leaf Fluttering In Wind!
sub listen {
  my $self = shift;
  $self = $self->singleton unless ref $self;
  my $args = ref $_[0] ? $_[0] : {@_};
  warn
    "Mojo::IOLoop->listen is DEPRECATED in favor of Mojo::IOLoop->server!\n";

  my $accept = delete $args->{on_accept};
  my $close  = delete $args->{on_close};
  my $error  = delete $args->{on_error};
  my $read   = delete $args->{on_read};
  my $id;
  $id = $self->server(
    $args => sub {
      my ($self, $stream, $id) = @_;

      my $c = $self->{connections}->{$id};
      $c->{close} = $close if $close;
      $c->{error} = $error if $error;
      $c->{read}  = $read  if $read;
      $stream->on(
        close => sub {
          my $c = $self->{connections}->{$id};
          $c->{close}->($self, $id) if $c->{close};
        }
      );
      $stream->on(
        error => sub {
          my $c = $self->{connections}->{$id};
          $c->{error}->($self, $id, pop) if $c->{error};
        }
      );
      $stream->on(
        read => sub {
          my $c = $self->{connections}->{$id};
          $c->{read}->($self, $id, pop) if $c->{read};
        }
      );
      $self->$accept($id) if $accept;
    }
  );

  return $id;
}

# DEPRECATED in Leaf Fluttering In Wind!
sub on_close { shift->_event(close => @_) }
sub on_error { shift->_event(error => @_) }

# DEPRECATED in Leaf Fluttering In Wind!
sub on_lock {
  warn
    "Mojo::IOLoop->on_lock is DEPRECATED in favor of Mojo::IOLoop->lock!\n";
  shift->lock(@_);
}

# DEPRECATED in Leaf Fluttering In Wind!
sub on_read { shift->_event(read => @_) }

# DEPRECATED in Leaf Fluttering In Wind!
sub on_unlock {
  warn <<EOF;
Mojo::IOLoop->on_unlock is DEPRECATED in favor of Mojo::IOLoop->unlock!
EOF
  shift->unlock(@_);
}

sub one_tick {
  my $self = shift;
  $self = $self->singleton unless ref $self;
  $self->timer(shift // '0.025' => sub { shift->stop });
  $self->start;
}

sub recurring {
  my ($self, $after, $cb) = @_;
  $self = $self->singleton unless ref $self;
  weaken $self;
  return $self->iowatcher->recurring($after => sub { $self->$cb(pop) });
}

# "Fat Tony is a cancer on this fair city!
#  He is the cancer and I am the… uh… what cures cancer?"
sub server {
  my $self = shift;
  $self = $self->singleton unless ref $self;
  my $cb = pop;

  # New server
  my $server = $self->server_class->new;
  my $id     = $self->_id;
  $self->{servers}->{$id} = $server;
  $server->iowatcher($self->iowatcher);
  weaken $server->{iowatcher};

  # Events
  weaken $self;
  $server->on(
    accept => sub {
      my $handle = pop;

      # Accept
      my $id = $self->stream(my $stream = $self->stream_class->new($handle));
      $self->$cb($stream, $id);

      # Enforce limit
      $self->max_connections(0)
        if defined $self->{accepts} && --$self->{accepts} == 0;
      $self->_not_listening;
    }
  );

  # Listen
  $server->listen(@_);
  $self->{accepts} = $self->max_accepts if $self->max_accepts;
  $self->_not_listening;

  return $id;
}

sub singleton { state $loop ||= shift->SUPER::new }

sub start {
  my $self = shift;
  $self = $self->singleton unless ref $self;

  # Check if we are already running
  croak 'Mojo::IOLoop already running' if $self->{running}++;

  # Mainloop
  my $id =
    $self->recurring($self->cleanup_interval => sub { shift->_cleanup });
  $self->iowatcher->start;
  $self->drop($id);

  return $self;
}

sub stop {
  my $self = shift;
  $self = $self->singleton unless ref $self;
  delete $self->{running};
  $self->iowatcher->stop;
}

sub stream {
  my $self = shift;
  $self = $self->singleton unless ref $self;

  # Find stream for id
  my $stream = shift;
  unless (blessed $stream) {
    return unless my $c = $self->{connections}->{$stream};
    return $c->{stream};
  }

  # Connect stream with watcher
  my $id = shift || $self->_id;
  my $c = $self->{connections}->{$id} ||= {};
  $c->{stream} = $stream;
  $stream->iowatcher($self->iowatcher);
  weaken $stream->{iowatcher};

  # Events
  weaken $self;
  $stream->on(close => sub { $self->{connections}->{$id}->{finish} = 1 });
  $stream->on(error => sub { $self->{connections}->{$id}->{finish} = 1 });
  $stream->on(read  => sub { $self->{connections}->{$id}->{active} = time });
  $stream->on(write => sub { $self->{connections}->{$id}->{active} = time });
  $stream->resume;

  return $id;
}

sub timeout {
  my ($self, $id, $timeout) = @_;
  $self = $self->singleton unless ref $self;
  return unless my $c = $self->{connections}->{$id};
  return $c->{timeout} unless defined $timeout;
  $c->{timeout} = $timeout;
  return $self;
}

sub timer {
  my ($self, $after, $cb) = @_;
  $self = $self->singleton unless ref $self;
  weaken $self;
  return $self->iowatcher->timer($after => sub { $self->$cb(pop) });
}

# DEPRECATED in Leaf Fluttering In Wind!
sub write {
  my ($self, $id, $chunk, $cb) = @_;
  warn <<EOF;
Mojo::IOLoop->write is DEPRECATED in favor of Mojo::IOLoop::Stream->write!
EOF
  return unless my $stream = $self->stream($id);
  return $stream->write($chunk) unless $cb;
  weaken $self;
  return $stream->write($chunk, sub { $self->$cb($id) });
}

sub _cleanup {
  my $self = shift;

  # Manage connections
  $self->_listening;
  my $connections = $self->{connections} ||= {};
  while (my ($id, $c) = each %$connections) {

    # Connection needs to be finished
    if ($c->{finish} && (!$c->{stream} || !$c->{stream}->is_writing)) {
      $self->_drop($id);
      next;
    }

    # Connection timeout
    $self->_drop($id)
      if (time - ($c->{active} || time)) >= ($c->{timeout} || 15);
  }

  # Graceful shutdown
  $self->stop if $self->max_connections == 0 && keys %$connections == 0;
}

sub _drop {
  my ($self, $id) = @_;

  # Timer
  return $self unless my $watcher = $self->iowatcher;
  return $self if $watcher->drop_timer($id);

  # Listen socket
  if (delete $self->{servers}->{$id}) { delete $self->{listening} }

  # Connection
  else {
    delete(($self->{connections}->{$id} || {})->{stream});
    delete $self->{connections}->{$id};
  }

  return $self;
}

# DEPRECATED in Leaf Fluttering In Wind!
sub _event {
  my ($self, $event, $id, $cb) = @_;
  warn "Mojo::IOLoop->on_* methods are DEPRECATED!\n";
  return unless my $c = $self->{connections}->{$id};
  $c->{$event} = $cb if $cb;
  return $self;
}

sub _id {
  my $self = shift;
  my $id;
  do { $id = md5_sum('c' . time . rand 999) }
    while $self->{connections}->{$id} || $self->{servers}->{$id};
  return $id;
}

sub _listening {
  my $self = shift;

  # Check if we should be listening
  return if $self->{listening};
  my $servers = $self->{servers} ||= {};
  return unless keys %$servers;
  my $i   = keys %{$self->{connections}};
  my $max = $self->max_connections;
  return unless $i < $max;
  if (my $cb = $self->lock) { return unless $self->$cb(!$i) }

  # Check if multi-accept is desirable and start listening
  $_->accepts($max > 1 ? 10 : 1)->resume for values %$servers;
  $self->{listening} = 1;
}

sub _not_listening {
  my $self = shift;

  # Check if we are listening
  return unless delete $self->{listening};
  return unless my $cb = $self->unlock;
  $self->$cb();

  # Stop listening
  $_->pause for values %{$self->{servers} || {}};
}

1;
__END__

=head1 NAME

Mojo::IOLoop - Minimalistic reactor for non-blocking TCP clients and servers

=head1 SYNOPSIS

  use Mojo::IOLoop;

  # Listen on port 3000
  Mojo::IOLoop->server({port => 3000} => sub {
    my ($loop, $stream) = @_;

    $stream->on(read => sub {
      my ($stream, $chunk) = @_;

      # Process input
      say $chunk;

      # Got some data, time to write
      $stream->write('HTTP/1.1 200 OK');
    });

  });

  # Connect to port 3000
  my $id = Mojo::IOLoop->client({port => 3000} => sub {
    my ($loop, $stream) = @_;

    $stream->on(read => sub {
      my ($stream, $chunk) = @_;

      # Process input
      say $chunk;
    });

    # Write request
    $stream->write("GET / HTTP/1.1\r\n\r\n");
  });

  # Add a timer
  Mojo::IOLoop->timer(5 => sub {
    my $loop = shift;
    $loop->drop($id);
  });

  # Start and stop loop
  Mojo::IOLoop->start;
  Mojo::IOLoop->stop;

=head1 DESCRIPTION

L<Mojo::IOLoop> is a very minimalistic reactor that has been reduced to the
absolute minimal feature set required to build solid and scalable
non-blocking TCP clients and servers.

Optional modules L<EV>, L<IO::Socket::IP> and L<IO::Socket::SSL> are
supported transparently and used if installed.

A TLS certificate and key are also built right in to make writing test
servers as easy as possible.
Also note that for convenience the C<PIPE> signal will be set to C<IGNORE>
when L<Mojo::IOLoop> is loaded.

=head1 ATTRIBUTES

L<Mojo::IOLoop> implements the following attributes.

=head2 C<client_class>

  my $class = $loop->client_class;
  $loop     = $loop->client_class('Mojo::IOLoop::Client');

Class to be used for opening TCP connections with the C<client> method,
defaults to L<Mojo::IOLoop::Client>.
Note that this attribute is EXPERIMENTAL and might change without warning!

=head2 C<iowatcher>

  my $watcher = $loop->iowatcher;
  $loop       = $loop->iowatcher(Mojo::IOWatcher->new);

Low level event watcher, usually a L<Mojo::IOWatcher> or
L<Mojo::IOWatcher::EV> object.
Note that this attribute is EXPERIMENTAL and might change without warning!

=head2 C<cleanup_interval>

  my $interval = $loop->cleanup_interval;
  $loop        = $loop->cleanup_interval(1);

Connection cleanup interval in seconds, defaults to C<0.025>.
Note that this attribute is EXPERIMENTAL and might change without warning!

=head2 C<lock>

  my $cb = $loop->lock;
  $loop  = $loop->lock(sub {...});

A locking callback that decides if this loop is allowed to accept new
incoming connections, used to sync multiple server processes.
The callback should return true or false.
Note that exceptions in this callback are not captured.

  $loop->lock(sub {
    my ($loop, $blocking) = @_;

    # Got the lock, listen for new connections
    return 1;
  });

=head2 C<max_accepts>

  my $max = $loop->max_accepts;
  $loop   = $loop->max_accepts(1000);

The maximum number of connections this loop is allowed to accept before
shutting down gracefully without interrupting existing connections, defaults
to C<0>.
Setting the value to C<0> will allow this loop to accept new connections
infinitely.
Note that this attribute is EXPERIMENTAL and might change without warning!

=head2 C<max_connections>

  my $max = $loop->max_connections;
  $loop   = $loop->max_connections(1000);

The maximum number of parallel connections this loop is allowed to handle
before stopping to accept new incoming connections, defaults to C<1000>.
Setting the value to C<0> will make this loop stop accepting new connections
and allow it to shutdown gracefully without interrupting existing
connections.

=head2 C<server_class>

  my $class = $loop->server_class;
  $loop     = $loop->server_class('Mojo::IOLoop::Server');

Class to be used for accepting TCP connections with the C<server> method,
defaults to L<Mojo::IOLoop::Server>.
Note that this attribute is EXPERIMENTAL and might change without warning!

=head2 C<stream_class>

  my $class = $loop->stream_class;
  $loop     = $loop->stream_class('Mojo::IOLoop::Stream');

Class to be used by C<client> and C<server> methods for I/O streams, defaults
to L<Mojo::IOLoop::Stream>.
Note that this attribute is EXPERIMENTAL and might change without warning!

=head2 C<unlock>

  my $cb = $loop->unlock;
  $loop  = $loop->unlock(sub {...});

A callback to free the accept lock, used to sync multiple server processes.
Note that exceptions in this callback are not captured.

=head1 METHODS

L<Mojo::IOLoop> inherits all methods from L<Mojo::Base> and implements the
following new ones.

=head2 C<client>

  my $id =
    Mojo::IOLoop->client(address => '127.0.0.1', port => 3000, sub {...});
  my $id = $loop->client(address => '127.0.0.1', port => 3000, sub {...});
  my $id = $loop->client({address => '127.0.0.1', port => 3000}, sub {...});

Open TCP connection with C<client_class>, which is usually
L<Mojo::IOLoop::Client>, takes the same arguments as
L<Mojo::IOLoop::Client/"connect">.
Note that this method is EXPERIMENTAL and might change without warning!

  Mojo::IOLoop->client({port => 3000} => sub {
    my ($loop, $stream, $error) = @_;
  });

=head2 C<defer>

  Mojo::IOLoop->defer(sub {...});
  $loop->defer(sub {...});

Invoke callback on next reactor tick.
Note that this method is EXPERIMENTAL and might change without warning!

=head2 C<delay>

  my $delay = Mojo::IOLoop->delay;
  my $delay = $loop->delay;
  my $delay = $loop->delay(sub {...});

Get L<Mojo::IOLoop::Delay> object to synchronize events.
Note that this method is EXPERIMENTAL and might change without warning!

  # Synchronize multiple events
  my $delay = Mojo::IOLoop->delay(sub { say 'BOOM!' });
  for my $i (1 .. 10) {
    $delay->begin;
    Mojo::IOLoop->timer($i => sub {
      say 10 - $i;
      $delay->end;
    });
  }

  # Wait for events
  $delay->wait;

=head2 C<drop>

  $loop = Mojo::IOLoop->drop($id);
  $loop = $loop->drop($id);

Drop anything with an id.
Connections will be dropped gracefully by allowing them to finish writing all
data in their write buffers.

=head2 C<generate_port>

  my $port = Mojo::IOLoop->generate_port;
  my $port = $loop->generate_port;

Find a free TCP port, this is a utility function primarily used for tests.

=head2 C<is_running>

  my $success = Mojo::IOLoop->is_running;
  my $success = $loop->is_running;

Check if loop is running.

  exit unless Mojo::IOLoop->is_running;

=head2 C<one_tick>

  Mojo::IOLoop->one_tick;
  $loop->one_tick;
  $loop->one_tick('0.25');
  $loop->one_tick(0);

Run reactor for roughly one tick and try not to block longer than the given
amount of time in seconds.

=head2 C<recurring>

  my $id = Mojo::IOLoop->recurring(0 => sub {...});
  my $id = $loop->recurring(3 => sub {...});

Create a new recurring timer, invoking the callback repeatedly after a given
amount of seconds.
This for example allows you to run multiple reactors next to each other.

  my $loop2 = Mojo::IOLoop->new(timeout => 0);
  Mojo::IOLoop->recurring(0 => sub { $loop2->one_tick });

Note that the loop timeout can be changed dynamically at any time to adjust
responsiveness.

=head2 C<server>

  my $id = Mojo::IOLoop->server(port => 3000, sub {...});
  my $id = $loop->server(port => 3000, sub {...});
  my $id = $loop->server({port => 3000}, sub {...});

Accept TCP connections with C<server_class>, which is usually
L<Mojo::IOLoop::Server>, takes the same arguments as
L<Mojo::IOLoop::Server/"listen">.
Note that this method is EXPERIMENTAL and might change without warning!

  Mojo::IOLoop->server({port => 3000} => sub {
    my ($loop, $stream, $id) = @_;
  });

=head2 C<singleton>

  my $loop = Mojo::IOLoop->singleton;

The global L<Mojo::IOLoop> singleton, used to access a single shared loop
instance from everywhere inside the process.

  # Many methods also allow you to take shortcuts
  Mojo::IOLoop->timer(2 => sub { Mojo::IOLoop->stop });
  Mojo::IOLoop->start;

=head2 C<start>

  Mojo::IOLoop->start;
  $loop->start;

Start the loop, this will block until C<stop> is called.

=head2 C<stop>

  Mojo::IOLoop->stop;
  $loop->stop;

Stop the loop immediately, this will not interrupt any existing connections
and the loop can be restarted by running C<start> again.

=head2 C<stream>

  my $stream = Mojo::IOLoop->stream($id);
  my $stream = $loop->stream($id);
  my $id     = $loop->stream($stream);

Get L<Mojo::IOLoop::Stream> object for id or turn object into a connection.
Note that this method is EXPERIMENTAL and might change without warning!

=head2 C<timeout>

  my $timeout = Mojo::IOLoop->timeout($id);
  my $timeout = $loop->timeout($id);
  $loop       = $loop->timeout($id => 45);

Maximum amount of time in seconds a connection can be inactive before getting
dropped, defaults to C<15>.

=head2 C<timer>

  my $id = Mojo::IOLoop->timer(5 => sub {...});
  my $id = $loop->timer(5 => sub {...});
  my $id = $loop->timer(0.25 => sub {...});

Create a new timer, invoking the callback after a given amount of seconds.

=head1 DEBUGGING

You can set the C<MOJO_IOLOOP_DEBUG> environment variable to get some
advanced diagnostics information printed to C<STDERR>.

  MOJO_IOLOOP_DEBUG=1

=head1 SEE ALSO

L<Mojolicious>, L<Mojolicious::Guides>, L<http://mojolicio.us>.

=cut
